Canon 75-300/4.0-5.6 Problem

[Holly]

Hey guys - I have had the Canon 75-300/4.0-5.6 for about 3 years now and it was my primary lense before getting the 50/1.8 and 100/2.8 macro. Needless to say - VERY well used. (translation - beaten up) :) Problem is: The last two times I used it I had a lot of trouble with AF - 1st being very dark restaurant - even the 100/2.8 had trouble with AF, and 2nd being outdoors around 5:30 (cloudy day - but not dark). I don't think I could have accidentally changed the focusing point because you have to go into the menu for that. Is this a common problem with this lense? Am I going to have to scrap it and go for the faster version? wink, wink

[LoungeLizard]

I've got this lens and it needs a fair amount of light and contrast to focus.

I had a problem last weekend with my 28-135IS not focusing. I have started to just use the center point focus, but for some reason it was really whacky. One of the other photographers there just said "it's probably her shirt, try focusing on something else." That worked perfectly. It turned out she was wearing a pink shirt with a bit of shine so there was very little contrast at all. That also reminded me that I had been misfocusing since I usually will focus/lock at about the chin/nose and recompose.

In the heat of battle (OK, shooting), you sometimes forget some things. I guess that's what separates the pros from the rest of us (that and the white lenses - Abel, you're not going to live this one down!)

[Holly]

I forgot about the contrast thing - thanks Jesus.

[saroy]

I had a LOT of trouble with the 75-300 IS version on my 10D a couple weeks back, and couldn't pinpoint quite what the trouble was, except perhaps the battery grip (which didn't make a whole lot of sense, but...) I used the 75-300 again yesterday *without* the battery grip attached, and had no trouble. I'm still not entirely convinced that it was the grip (another difference was that when I had problems I was in Av mode, yesterday I was in Tv mode), but signs are pointing to it.